The D.C. Water and Sewer Authority is conducting its annual program to flush water mains throughout the city, a procedure designed to remove sediment and improve water quality.

From 10 p.m. to 6:30 a.m. Sunday through Thursday, WASA crews are opening fire hydrants in designated neighborhoods and flushing water.

The water supply to customers is not shut off during the flushing.

Customers might notice some water discoloration early in the morning. If that happens, WASA recommends that residents open the cold water tap and allow the water to flow slowly until it is clear.

Customers should not run hot water or do laundry during the flushing. If the hot water becomes discolored, WASA recommends flushing the hot water tank by opening the valve at the bottom of the tank.

The flushing program will continue through November.

These neighborhoods, with boundary streets, are scheduled for flushing the week starting Sunday, according to information provided by WASA:

* ANC 4C (work area in Northwest, bounded by Ingraham Street, Illinois Avenue, Buchanan Street and Georgia Avenue).

* ANC 1A (work area in Northwest, bounded by Spring Road, Georgia Avenue, Kenyon Street and Holmead Place).

* ANC 1A (work area in Northwest, bounded by Quincy Street, Park Place, Park Road and Georgia Avenue).

* ANC 3D (work area in Northwest, bounded by Reservoir Road, 44th Street, P Street and Canal Road).

* ANC 3B (work area in Northwest, bounded by Whitehaven Parkway, Wisconsin Avenue, Reservoir Road and 39th Street).

* ANC 3B (work area in Northwest, bounded by S Street, 31st Street, P Street and 35th Street).

* ANC 7D (work area in Northeast, bounded by Nannie Helen Burroughs Avenue, 50th Street, East Capitol Street and 47th Street).

* ANC 7C (work area in Northeast, bounded by Dix Street, 57th Street, East Capitol Street and 50th Street).

* ANC 7A (work area in Southeast, bounded by Massachusetts Avenue, 35th Street, Anacostia Avenue and Minnesota Avenue).

* ANC 7A (work area in Southeast, bounded by F Street, Minnesota Avenue, Nash Place and Fairlawn Avenue).

* ANC 6C (work area in Southeast, bounded by Ridge Place, Minnesota Avenue, W Street and Fairlawn Avenue).

* ANC 8A (work area in Southeast, bounded by W Street, Martin Luther King Avenue, Stevens Road and South Capitol Street).

* ANC 2D (work area in Southwest, bounded by Independence Avenue, 4th Street, M Street and 4th Street).

* ANC 2D (work area in Southeast, bounded by E Street, 11th Street, M Street and South Capitol Street).

* ANC 7B (work area in Southeast, bounded by Fort Dupont Street, Southern Avenue, Pennsylvania Avenue and Alabama Avenue).

* ANC 7B (work area in Southeast, bounded by Massachusetts Avenue, 39th Street, Pennsylvania Avenue and 33rd Street).

* ANC 2A (work area in Northwest, bounded by K Street, 24th Street, E Street and 27th Street).

* ANC 2A (work area bounded by G Street, 17th Street, Constitution Avenue and 23rd Street).

* ANC 4C (work area in Northwest, bounded by Kennedy Street, Fifth Street, Emerson Street and Illinois Avenue).

* ANC 4C (work area in Northwest, bounded by Missouri Avenue, Third Street, Gallatin Street and Fifth Street).

* ANC 6B (work area in Southeast, bounded by E Street, 11th Street, M Street and South Capitol Street).

* ANC 2D (work area bounded by M Street, 1st Street SE, V Street SW and Maine Street SW).

* ANC 7C (work area in Northeast, bounded by Sheriff Road, 48th Street, Gault Place and Minnesota Avenue).

ANC 7C (work area in Northeast, bounded by Meade Street, 50th Street, Sheriff Road and Minnesota Avenue).

For information, call the WASA Water Quality Office, 202-612-3440, 8 a.m.- 4 p.m. In an emergency, call WASA's 24-hour hotline, 202-612-3400.